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ANSI/AAMI ST98: A Guideline for Cleaning Validations of Reusable devices

The new ANSI/AAMI ST98 standard, published in 2022, is a long-awaited clarification of the strategy for cleaning validations for reusable medical devices. The standard serves as a key regulatory guideline to support device manufacturers in their regulatory submissions.

For a long time, the strategy for manufacturers validating a reusable medical device’s cleaning instructions has been unclear. The main reason being that the previous AAMI TIR 30 standard had not been recognized by the United States Food and Drug Administration (FDA) for several years. Additionally, there was a lack of ISO referencing in FDA Guidance for reprocessing medical devices, which made the situation complicated for medical device manufacturers. Since the publication of the new AAMI ST98 standard, cleaning validations now have their own specific guideline.



When developing a new reusable medical device, or modifying an existing one, the efficacy of the reprocessing instructions recommended by the manufacturer must be validated. To achieve this, the instructions for use (IFU) must highlight all of the stages requested for the reprocessing (cleaning, disinfection and sterilization-as applicable) and each of the required stages must be individually validated according to specific standards.


Cleaning Validation and Device Classification

A mandatory risk analysis must be conducted to determine the appropriate classification of a device’s criticality. This analysis takes into account factors such as the device’s characteristics, design and actual clinical conditions of use. The ANSI/AAMI ST98 standard describes this classification considering the characteristics of the device.

This analysis is then used throughout the entire validation process of the device to justify the relevance of each choice made during laboratory testing, including sampling, selection of the relevant markers and the procedure for soiling.



Sampling is the first strategic step that must be justified in liaison with the criticality of the device. The sampling is related to the cleaning challenge. The number of samples can be increased to reflect the device’s complexity, risk for patient or enhance the cleaning robustness.


Simulated Use Cycles

All test and control samples must undergo a minimum of six (6) simulated use cycles. These cycles should encompass all reprocessing steps (cleaning, disinfection and sterilization), as recommended by the manufacturer. The cycles can be conducted either automatically or manually following the instructions provided in the IFU. The purpose of these cycles is to:

  • Mimic the actual wear and tear experienced by the devices during the reprocessing cycles
  • Imitate the buildup of soil residues throughout the reprocessing cycles, which may impact the final measurement point’s residual rates


Efficacy Cycles

The test samples must be subjected to three (3) independent efficacy cycles. Only the reprocessing phases corresponding to the cleaning step are applied in these cycles. These cycles aim to evaluate the effectiveness of the cleaning steps alone, with the selected markers observed as endpoints.


Residual Marker Analysis

Non-critical devices can be subjected to visual inspection only. This visual inspection must attest to the efficacy of the cleaning procedure. For critical and semi-critical devices, specific residual analyses of selected markers need to address the evaluation of potential soil residues. The selection of these markers must reflect the actual clinical use of the device. It is recommended to select two different markers. Any risk of blood contamination, whether slight or due to misuse of the device, necessitates the use of the hemoglobin marker.

The ANSI/AAMI ST98 standard better defines the strategy for validating the efficacy of cleaning instructions for reprocessing a reusable medical device and should be carefully followed for acceptance by regulatory authorities. This standard also emphasizes that any strategy selected has to consider the device’s characteristics and the actual clinical conditions of use. Manufacturers now need to carry out appropriate risk analyses and be able to justify any choice from sampling to soil presence during efficacy testing. Unlike sterilization validation, for which results are binary (pass/fail criteria), cleaning efficacy is defined according to the test procedure and acceptability thresholds. Even when carried out in the worst-case scenario, the test procedures have to remain representative of the use of the device. They must be consistent with the device’s actual use, level of risk and criticality. The completion of an appropriate cleaning validation requires a full understanding of the expectations in the new standard.

However, the ANSI/AAMI ST98 describes requirements for FDA acceptance only. The lack of ISO guidelines does not clarify the situation for the European market, resulting in continued confusion in Europe. Nevertheless, knowing that the current trend is to converge US and European regulation, it seems clear that European authorities will eventually adopt the FDA recommendations for cleaning validation. The ANSI/AAMI ST98 is intended to become a new ISO standard for several other medical device testing procedures.


How Can NAMSA Help?

With world-class CRO testing capabilities, global state-of-the-art facilities and unmatched expertise, NAMSA is well-equipped to support your cleaning validation requirements. Our experienced and dedicated team can help you to navigate regulatory obstacles and recommend testing requirements according to the new ANSI/AAMI ST98 standard. Contact us today to begin your cleaning validation project.

Frédéric Cadoret, PhD

Frédéric Cadoret is a microbiology expert who joined NAMSA in 2019. With over nine years of experience in microbiology in vitro testing, he provides support to medical device manufacturers in microbiological evaluations and submissions to Notified Bodies. Frédéric holds a PhD in microbiology, vegetal biology, and biotechnology. He conducts training sessions on microbiology according to ISO standards and AAMI guidelines, and offers consulting services for reprocessing validation projects. He also assists manufacturers in developing appropriate bioburden, sterility, and endotoxin strategies for single-use devices. In addition, Frédéric lectures to Master degree students at the Université de Montpellier and has developed new microbiological testing methods.